Switch construction



u y 3, 1956 E. A. LINK SWITCH CONSTRUCTION 2 Sheets-Sheet 1 Filed May 21 1951 INVENTOR. .EDWJNALJNTK 44 7'70/P/VEY July 3, 1956 E. A. LINK 2,753,412

SWITCH CONSTRUCTION Filed May 21, 1951 2 Sheets-Sheet 2 mm I 32 23 IN VEN TOR.

EDWIN A-L1Nzc ATTG/P/VEY United States Patent SWITCH CONSTRUCTION Edwin A. Link, Milwaukee, Wis assignor, by mesne assignments, to R T & E Corporation, a corporation of Wisconsin Application May 21, 1951, Serial No. 227,402

13 Claims. (Cl. 20ti-67) This invention relates to switches and more particularly to a snap-action switch construction of the type adapted primarily for use in the making and breaking of electrical contacts carrying high voltages.

One outstanding use for a switch construction of this type is found in conjunction with line voltage regulators, having a high input voltage, in some instances 7200 volts or higher, and an output voltage of approximately 120 volts, now in common use on rural power distribution lines.

The present invention provides a switch construction which is sturdy, durable and economical and one which aflords advantageous operating characteristics as it is capable of breaking possible welds between contacts, shifting the position of the movable contact with great rapidity, to lessen the time of circuit break, and providing a posi tive driving force to insure the completion of the shifting movement of the movable contact.

The primary object of the present invention resides in the provision of a new and improved switch construction having advantageous operating characteristics.

Another object of the present invention resides in the provision of a new and improved switch construction embodying novel switch arm construction.

Another object of the invention resides in the provision in a new and improved switch construction of an articulated switch arm including a movably mounted member and a contact carrying member movably associated therewith.

Another object of the invention resides in the provision in a new and improved switch construction of an articulated switch arm including a lost-motion connection between the members of the arm.

Another object of the invention resides in the provision in a new and improved switch construction of stop means on the articulated switch arm for limiting the relative movement between the members of the arm.

Another object of the present invention resides in the combination with a new and improved switch construction of a movable switch operating element.

Another object of the invent on resides in the provision in a new and improved switch construction of yieldable connecting means between the switch operating element and the articulated switch arm arranged to transmit the motion of the switch operating element to effect the movement of the articulated switch arm to shift the electrical connections between the contacts of the switch.

Another object of the invention resides in the provision of a yieldable connecting means between the switch operating element and the articulated switch arm effective to exert a motivating force upon the articulated arm, selectively, either to retain it in one position or to effect its movement to another position.

Another object of the invention resides in the new and improved combination with an articulated switch arm and an operating element of a yieldable connecting means, in the form of a coil spring, etween the arm and the operating element to maintain tension on the articulated switch arm at all times.

Another object of the invention resides in the provision in a new and improved switch construction of a novel arrangement of parts whereby movement of the switch operating element effects a load-and-Lre action of the yieldable connecting means to produce a snapaction hammer blow movement of the switch contact from one operating position to another.

Another object of the invention resides in the provision in a new and improved switch construction of a novel arrangement of parts whereby the initial movement of the articulated switch arm effects a turning action between the associated contacts of the switch to break any possible weld between the contacts and facilitate the shifting of the switch contact under the influence of continued movement of the articulated switch arm.

Other objects and advantages will become apparent from the following description of the illustrative embodiment of the invention shown in the accompanying drawings.

In the drawings:

Figure 1 is a front elevational view of a switch construction embodying the teachings of the present invention and having parts broken away to show the switch arm in full lines in one position and in dotted lines in another position;

Fig. 2 is a verical sectional view, taken on the line 22 of Fig. 1, showing a driving means for the switch operating element and a yieldable connecting means, between the switch operating element and the articulated switch arm, operative to impart a snap-action, hammer blow movement to the switch arm in response to movement of the switch operating element;

Fig. 3 is a horizontal sectional view, taken on the line 33 of Fig. 1, showing the relative positioning of the power and load line contacts of the switch together with associated electrical connections and the bridging contact which is movable to connect, selectively, the power line with one or another of the load line contacts;

Fig. 4 is a fragmentary front elevational view of the switch construction showing the load line contacts and associated electrical connections;

Fig. 5 is a fragmentary rear elevational view of the switch construction showing the power line contacts and associated electrical connections;

Fig. 6 is a fragmentary vertical sectional view, taken on the line 66 of Fig. 1, showing the rockable mounting of the articulated switch arm together with the connection between its parts and the yieldable coupling means between it and the switch operating element;

Fig. 7 is a horizontal sectional view, taken on the line 77 of Fig. 1, through the articulated switch arm showing in top plan the lost-notion connection between the articulated parts of the switch arm;

Fig. 8 is a horizontal sectional view through the articulated switch arm, taken on the line 8-8 of Fig. 1, showing in bottom plan the lost-motion connection between the articulated parts of the switch arm; and

Fig. 9 is a horizontal sectional view through a member of the articulated switch arm, taken on the line 9-9 of Fig. 1, showing the mounting of the bridging contact on the contact carrying member of the switch arm.

For illustrative purposes in the accompanying drawings, I have chosen, arbitrarily, to show a switch construction embodying the teachings of the present invention in a form adapted primarily for use in conjunction with a single step line voltage regulator having a power input voltage of some 7200 volts. In devices of this type, suitable voltage responsive control means function automatically, under persisting excessive voltage fluctuations in the load line, to effect the change of position of the 3 switch to alter the operating characteristics of the line voltage regulator in accordance with the service demands made upon the load line.

'While'the switch construction of the present invention is particularly well adapted for'use in conjunction with line voltage regulators, it is to be understood that it may be employed advantageously in many other applications and more especially those wherein it is desirable to make andbreak electrical contacts carrying'relatively high voltages.

Referring more particularly to Fig. 1 of the accompanying drawings, it will be noted that the switch construction comprises a unitary structure adapted for mounting in the steeltank of a voltage regulator in a position in which the switch contacts maybe submerged in oil.

The switch constructioncomprises generally 'a switch supporting structure 10,- a plurality of switch contacts 11, '11 and 12, 12 mounted in spaced relationship and adapted respectively for connection with power and load lines, a movable switch arm 13, a switch operating element 14, a driving means 15 for effecting the movement of the switch operating element, and a mounting bracket '16 'by which'the switch assembly may be retained in 'desired position with respect to the device with which it is associated.

The supporting structure 11 for-the switch assembly *cornprises'a pair of plates 17 and 18 formed of suitable insulating material, such as high grade canvas base phenolic board, provided with a plurality of aligned holes 19 adapted to receive anchoring bolts 20 and arranged to be retained in parallel spaced relationship by means of a plurality of spacer bushings 21, also formed of insulating material, adapted to be slid on to the bolts 21) and lie between the adjacent surfaces of the front and rear plates 17 and 18 respectively. The plates 17 and 18 are also provided with aligned apertures 22 and 23, respectively, disposed in lateral spaced relationship and located in the lower portion of the plates. These apertures 22 and 23 serve, respectively, as recesses through which load line contacts 12, 12' and the power line contacts 11, 11' extend. The plates 17 and 18 are further provided with aligned holes 24 and 25, respectively, disposed above and between the apertures 22 and 23. The holes 24 and 25 serve as bearings for rockably mounting'the switch arm '13. The plate 18 also contains an aperture 26 located above the hole 25 and adapted to provide anopening in which the switch operating element 14 may be positioned. The'plate 18 also servesto carry the mounting bracket 16 which is provided with a depending flange 27 adapted to be attached to the upper portion of the plate by means of bolts 28. The mounting bracket includes an upwardly directed rear flange portion 29 provided with an aperture 30 adapted to receive any suitable anchoring means to retain the switch assembly in desired posi- "tion'with'respect to the device with which it is associated.

The several electrical contacts 11, 11,'12 and 12' are identical in structure and mode of mounting and hence adescription of one will suffice for all. Each contact includes a yieldable spring blade 31 having one end portion'ada'pted'for fixed positioning on the outer surface of its associated mounting plate 17 or'13, as the case may be, by the application of a pair of spaced anchoring bolts 32.

'Thefree end ofthe blade 31 extends over the'contact receiving aperture 22 or 23 andis provided with a hole "'adaptedto receive a stud 33 projecting from the rear surface of the contact. The mounting stud 33 may be in 'the'formof'arivet deformable to retain the contact in "proper position on the blade 31 and simultaneously anchor -one-termina1 of a current carrying connector 34 to the 'contact' while-the other end of the connector 34 is retained on one of the anchoring bolts 32. A' current carry- The switch arm 13, chosen for illustrative purposes and embodying the teachings of the present invention, comprises an articulated structure including a rockably mounted member 36 and a contact carrying member 37. The member 36 is preferably in the form of a casting having a substantially tubular lower portion provided with a vertically disposed oblong passage 38 adapted to house the upper portion of the tubular contact carrying member 37. The upper portion of the member 36 is bifurcated and includesa pair of upwardly directed spaced arms 39 each provided with'a horizontally arranged outwardly extending pivot pin 41). The pins 49 are arranged in axial alignment and adapted for receipt in the aligned holes24 and 25 in the plates 17 and 18, respectively, to provide a rockable mounting for the member 36.

The contact carrying member 37 of the switch arm 13 is preferably formed of a hollow tubular piece of dielectric material having its upper portion extending through the oblong passage 38 formed in the member 36. An articulated connection is provided between the memers 36 and 37 of the switch arm 13 by the rockable mounting of the member 37 on a pivot pin 41 which is anchored in the member 36 and passes through a hole 42 formed in the contact carrying member 37 adjacent its upper extremity. The cooperating relationship between the members 36 and 37 is such that the amount of freemovement, or lost motion, between the articulated parts of the switch arm 13 is limited by the contact between the outer surface of the member 37 with theend Walls of the oblong passage 33. A bridging contact 43 mounted in any suitable manner, such as by the application of a rivet 44, adjacent the lower or free end of the member 37 provides the means by which the respective pairs of power line and load line contacts 11, 11' and 12, 12 may be selectively connected by the operation of the switch. The amount of permissable movement of the articulated switch arm 13 is limited by the provision of a pair of abutment or stop members 45 and 46 located in laterally spaced relationship and constructed and retained in position between the plates 17 and 18 in the manner of the spacer bushings 21, previously described. The stop 45 is located above the contacts 11 and 12 and positioned so that abutment between it and the contact carrying member 37 will serve to establish the desired electrical connection of the bridging contact 4-3 with the powerand load line contacts 11 and 12 respectively, when the switch assumes the position indicated in dotted lines in Fig. 1. In like manner, the stop 46 is located above the contacts 11 and 12' and functions in the manner just described to establsh the desired electrical connection of the bridging contact 43 with the power and load line contacts 11 and 12 respectively, when the switch assumes the position shown in full lines in Fig. 1.

The switch operating element 14 is positioned in the aperture 26 formed in the rear plate 18 and comprises a crank arm 47 including a rearwardly projecting hub portion 48 adapted to be secured to a rotatable shaft'by means of an anchoring pin 49 and a forwardly projecting crank pin 51 located adjacent the free end of the crankarm 47.

The yieldable connecting means for coupling the switch operating element 14 with the switch arm 13 comprises a coil spring 51, under tension, having one end anchored on the crank pin 5%) of the switch operating element 1 and having its other end anchored on the pivot pin 41 which serves to connect the articulated members 36 and 37- of the switch arm 13. The yieldable connecting means which couples the switch operating element 14 and the articulated switch arm 13 serves as a means for maintaining tension on the switch arm at all times and when the connecting means is moved to an over center position under the influence of the operating element 14 it provides the means by which the contact carrying member 37 of the switch arm13 is impelled with snap'a'ctionand hammer blow force to shift the position of the bridging contact 43.

The driving means, chosen for illustrative purposes, for effecting partial rotation of the switch operating element 14 comprises an electric motor 52, positioned behind the mounting plate 18 and attached to the under side of the mounting bracket 16 by means of screws 53. The motor 52 is further secured rigidly in desired position by means of screws 54 which pass through the plate 18 and spacer collars 55. In order to obtain the desired rate of movement of the switch operating element 13, the motor 52 is provided with a suitable gear reduction transmission train including a driven gear 56 secured to a shaft 57 by means of a pin 58. The shaft 57 is journalled in bearings 59 mounted in the frame of the motor 52 and is provided with a forwardly projecting portion which extends through the aperture 26 in the plate 18 to afford a mounting for the switch operating element 14.

The simplicity of the several cooperating parts of the present switch construction obviates the necessity for a detailed description of assembly procedures.

The electrical connections for the switch construction comprise a power input conductor 60 having one end attached to a power line and its other end electrically connected to the power contact 11, a conductor 61 connecting the contacts 11 and 11 serves to provide the contact 11 with power line voltage. A load line conductor 62 is connected to the contact 12 and serves as a source of power for the load line to which it may be connected when the switch is moved to the position in which the contacts 11 and 12 are bridged by the contact 43. A similar load line conductor 63 is connected to the contact 12 and serves as a source of power for the load line to which it may be connected when the switch is moved to the position in which the contacts 11' and 12 are bridged by the contact 43.

A brief description of the operation of the switch should serve to emphasize its numerous advantages. At the outset, it should be understood that the embodiment of the switch construction chosen for illustrative purposes is of the type adapted primarily for use in the making and breaking of electrical contacts carrying high voltages and particularly well adapted for use in conjunction with line voltage regulators of the type operative automatically to maintain load line volt-ages within permissible limits of fluctuations to energize the switch operating motor 52 to effect a change of position of the switch arm 13 and alter the electrical connections between the power and load lines, selectively, to insert a booster coil winding of the regulator into series connection between the power line and one of the load lines to increase the load line voltage in response to a persisting excessive voltage drop in the load line or to cut the booster coil winding of the regulator out of series connection between the power line and load line in response to a persisting ex- .cessive increase in load line voltage. For the purpose of describing the operation of the switch, let us assume that the load line voltage on the load side of the regulator is within the permissible limits of fluctuation. With this condition existing, the switch arm 13 will remain in the particular position in which it may be located at the time. If it happens to be in the position indicated in full lines in Fig. 1, it will remain in this position with the contact 43 bridging the gap between the contacts 11 and 12' and the booster coil of the regulator will be ineffective to alter the voltage on the load line side of the regulator. However, should the demand on the load side of the regulator be increased and the load line voltage be thereby decreased beyond the permissible limit of fluctuation, as dictated by the adjustment of the voltage sensitive control device, the voltage sensitive control device will respond to this condition by closing a control circuit to energize the switch operating motor 52 with the result that the switch operating element 14 will be rotated in ,a clockwise direction, referring to Fig. 1. If the demand for increased voltage on the load side of the regulator persists for a sufiicient period of time to permit the switch operating element 14 to be rotated from its normal neutral position, as indicated in dot-dash lines in Fig. 1, to a point where it carries the yieldable coupling means or coil spring 51 over center, that is beyond an imaginary line drawn through the centers of the pivot pin 41 and the common axis of the pins 40, the tension of the coil spring will cause the switch arm 13 to be thrown to the dotted line position in Fig. 1 wherein the contact 43 will then bridge the gap between the contacts 11 and 12 and cause the booster coil winding of the regulator to become effective to raise the voltage on the load side of the regulator. This position of the switch will persist until such time as the voltage on the load side of the regulator exceeds the maximum adjusted voltage of the voltage sensitive control device at which time the control device will again function to energize the switch operating motor 52 and cause it to rotate the switch operating element 14 in a counter-clockwise direction, referring to Fig. 1. If the excessive voltage on the load side of the regulator persists for a sufficient time to permit the switch operating element 14 to be rotated in a counter-clockwise direction from its normal neutral or vertical position, to a point where it carries the coil spring 51 over center, as previously described, the switch will be thrown to the full line position shown in Fig. 1 wherein the booster coil winding of the regulator will again become ineffective to alter or vary the voltage on the load side of the regulator. Having covered the general operation of the switch, let us now direct our attention to some of the important structural and functional features of the switch. One of the important structural and functional features of the switch is found in the provision of a yieldable coupling means in the form of a coil spring which connects the switch operating element 14 with the switch arm 13. This coil spring 51 serves multiple purposes in the present switch construction; it not only provides the medium through which the motion of the switch operating element is transmitted to the switch arm 13 but also serves to bias the switch arm 13 at all times and further provides the means by which the snap-action of the switch is obtained. Another important feature of the switch is found in the articulated form of the switch arm 13. The articulation of the members 36 and 37 is so arranged that it affords a lost-motion connection between them so that the initial movement of the articulated switch arm 13 under the action of the coil spring 51 will take up the lost-motion between the members 36 and 37 and in so doing will effect a rocking action or turning of the contact 43 with respect to the contacts 11 and 12 or 11 and 12' with which it is in contact to break any possible weld that might have formed between them. Continued movement of the articulated switch arm 13 under the action of the coil spring 51 effects a snap-action of the bridging contact 43 from one pair of line and load contacts to the other pair of line and load contacts to thus provide a substantially instantaneous shift of the bridging contact 43 from one position to another with the result that the break in the circuit is of extremely short duration. Another feature of the switch construction is found in the spring mounting of the several line and load contacts to insure the establishment of pressure contact between them and the bridging contact to provide a good electrical contact between their abutting surfaces. A further feature of the switch construction lies in the arrangement of the switch operating element with respect to the articulated switch arm and the coupling means for connecting these parts. The amount of movement of the switch operating element is controlled automatically by means associated with the switch driving motor 52 and the limits of the movement of the switch operating element are shown in full and dotted lines in Fig. 1. Additional control means associated with the motor 52 functions to return the switch operating element 14 to a neutral position, indicated in dot-dash lines in Fig. 1 after the completion of each shift: ing operation .of the articulated. switch arm 13. As the result of this arrangement, it will be noted that the coil spring coupling means. 51 between the switch operating element 14 and the articulated switch arm 13 is always under tension and thus serves adequately to retain the articulated switch arm 13 in either contact establishing position by urging the contact carrying member 37 against one or the other of the stops 45 or 46. As the switch operating element 14 moves from its neutral position to effect the movement of the articulated switch arm 13 in one direction or the other, as the case may be, it will be noted that the tension of the coil spring 51 is increased and hence when the movement of the switch operating element 14 has progressed far enough to move the coil spring 51' over center, the tension of the coil spring has been increased or loaded so that as it passes beyond a dead center position it will efiect a snap-action shifting movement of the articulated switch arm 13 to alter the position of the bridging contact 4-3 and change the switch connections.

From the foregoing description of an illustrative embodiment of the present invention, it will be noted that a new and improved switch construction has been provided which contains a combination of parts cooperating in a novel manner to provide a simple and effective switch which functions to combine snap-action switching operation with improved means for breaking possible welds between cooperating contacts to insure long life and efficient. operation of the switch.

While the switch construction chosen for illustrative purposes and embodying the teachings of the present invention has been described in considerable detail in the foregoing specification, it is to be understood that various changes may be made in its embodiment without departing from or sacrificing any of the advantages hereinafter claimed.

I claim:

1. A switch construction comprising the combination with a plurality of power and load line contacts arranged in spaced pairs and a bridging contact movable to establish electrical connection between different pairs of said power'and load line contacts, of an articulated switch arm structure including a pivotally mounted member and a bridging contact carrying member pivotally associated with said pivotally mounted member, a movable switch operating element, and a yieldable motion transmitting coupling means between said switch operating element and said articulated switch arm whereby movement of said switch operating element effects relative angular comprises a coil spring.

'3. A switch construction comprising the combination with apower line contact, a plurality of load line contacts and a bridging contact movable to establish electrical connection selectively between said power line contact and one or another of said load line contacts, of an articulated switch arm structure including a pivotally mounted member and a bridging contact carrying member pivotally connected with said other pivotally mounted member, a movable switch operating element, a yieldable motion transmitting coupling means connecting said switch operating element and said articulated switch arm whereby movement of said switch operating element 'effectsrelative angular movement in a common plane between the members of said articulated switch arm to 8 l impart a torsional movement between the abutting surfaces of said bridging contact and said pair of power and load line contacts to facilitate the breaking of the established electrical contactfollowed by a hammer blow snap-action movement of said switch arm under the action of said coupling means to shift the electrical connection from said power line contact from one to another of said load line contacts, and stop means for limiting the extent of movement of said articulated switch arm.

4. A switch construction comprising the combination with a power line contact, a plurality of load line contacts and a bridging contact movable to establish electrical connection selectively between said power line contact and one or another of said load line contacts, of an articulated switch arm structure including a pivotally mounted member and a bridging contact carrying member pivotally connected with saidother pivotally mounted member, a movable switch operating element, and a yieldable motion transmitting coupling means connecting said switch operating element and said articulated switch arm whereby movement of said switch operating element efiiects relative rocking, movement in a common plane between the pivotally connected portions of said articulated switch arm to impart a torsional movement between the abutting surfaces of said bridging contact and said power and load line contacts to facilitate the breaking of the establishedelectrical contact followed by a hammer blow snapaction of said articulated switch arm under the action of said yieldable motion transmitting coupling means to shift the electrical connection of said power line contact from one to another of said load line contacts.

5. A switch construction as set forth in claim 4, in which the yieldable motion transmitting coupling means comprises a coil spring.

6. A switch construction comprising the combination with a power line contact, a plurality of load line contacts and a bridging contact movable to connect said power line contact with one or another of said load line contacts, of an articulated switch arm including a pivotally mounted member, a bridging contact carrying member pivotally mounted on said other pivotally mounted member, a lost-motion connection between said members including stop means on one of said members cooperating with the other of said members for limiting the amount of relative angular movement between said members in a common plane, a movable switch operating element, and a yieldable motion transmitting coupling means between said switch operating element and said articulated switch arm whereby movement of said switch operating element effects relative angular movement in a common plane between the members of said articulated switch arm within the limits defined by said stop means to impart a torsional movement of said bridging contact with respect to the abutting surfaces of said power and load line contacts to facilitate the breaking of the electrical contact followed by a hammer blow snap-action movement'of said articulated switch arm under the action of said motion transmitting coupling'means to shift the connection of said power line contact from one to another of said load line contacts.

7. A switch construction as set forth in claim 6, in which the yieldable motion transmitting coupling means comprises a coil spring.

8. Asnap-action switch construction comprising a pair of laterally spaced electrically connected power line contacts, a plurality of laterally spaced load line contacts, a bridging contact for selective movement into frictional engagement with and between one of said power line contacts and one of said load line contacts, an articulated switch arm including a pivotally mounted member, a contact carrying member, pivotally mounted on said other pivotally mounted member, and a lost-motion connection between said members effective to permit limited angular movement between said members in a common plane, a

'movable switch operating-element, and a yieldable conheating means between said switch operating element and said articulated switch arm whereby movement of said switch operating element eflects relative angular movement in a common plane between the pivotally connected members of said articulated switch arm within the limits of the lost-motion connection between said members to impart a torsional movement of said bridging contact with respect to the abutting surfaces of the cooperating power and load line contacts to facilitate the breaking of the established electrical contact followed by a hammer blow snap-action movement of said articulated switch arm under the action of said connecting means to shift the position of said contact carrying member to alter the switch connections.

9. A snap-action switch construction as set forth in claim 8, in which the yieldable connecting means comprises a coil spring.

10. A pivot type snap-action switch construction comprising a pair of electrically connected power line contacts disposed in lateral spaced relationship, a pair of load line contacts disposed in lateral spaced relationship and positioned respectively in alignment with one or the other of said load line contacts, an articulated switch arm including a pivotally mounted member, a bridging contact carrying member pivotally mounted on said other pivotally mounted member, adapted for selective posi tioning between one of said power line contacts and one or the other of said load line contacts and a lost-motion connection between said members, a movable switch operating element, and a yieldable connecting means between said switch operating element and said articulated switch arm whereby the movement of said switch operating element is transmitted through said yieldable connecting means to cause relative angular movement in a common plane between said pivotally mounted members of said articulated switch arm to impart a torsional movement of said bridging contact with respect to the abutting surfaces of said power and load line contacts to facilitate the breaking of the established electrical connection and continued movement of said articulated switch arm serving to effect a hammer blow snap-action movement of said articulated switch arm to shift the position of said contact carrying member to alter the switch connections.

11. A pivot type snap-action switch construction as 10 set forth in claim 10, in which the yieldable connecting means comprises a coil spring.

12. A pivot type snap-action switch construction comprising an articulated switch arm including a pivotally mounted member, a contact carrying member pivotally mounted on said other pivotally mounted member, and a lost-motion connection between said members including means for limiting the extent of relative movement between said members, a movable switch operating element, and a yieldable connecting means between said switch operating element and said articulated switch arm whereby movement of said switch operating element effects movement of said articulated switch arm, the initial movement of said articulated switch arm serving to take up the lost-motion of the connection between the members of said switch arm and effect a torsional movement between the abutting surfaces of the switch contacts to break any possible weld between the contacts and continued movement of said articulated switch arm serving to efiFect a hammer blow snap-action shifting of the position of said contact carrying member under the influence of said yieldable connecting means to alter the switch connections.

13. A pivot type snap-action switch construction as set forth in claim 12, in which the yieldable connecting means comprises a coil spring.

References Cited in the file of this patent UNITED STATES PATENTS 751,174 Irish Feb. 2, 1904 1,001,796 Young Aug. 29, 1911 1,141,847 Stahl June 1, 1915 2,082,794 Ebert et a1. June 8, 1937 2,115,069 Hall Apr. 26, 1938 2,269,171 Benander Jan. 6, 1942 2,308,026 Rawlins Ian. 12, 1943 2,318,298 Dorfman et a1. May 4, 1943 2,354,282 Shaw July 25, 1944 2,418,965 Blair Apr. 15, 1947 2,485,399 Martin Oct. 18, 1949 2,514,839 Caswell July 11, 1950 2,596,893 Finizie May 13, 1952 FOREIGN PATENTS 344,435 Great Britain Mar. 2, 1931 

